Cardiac Quiz Flashcards
What two factors determine mean arterial blood pressure?
1) CO (HR x SV)
2) SVR
What two factors determine cardiac output?
1) SV
2) HR
CO= SV x HR
The interplay of what 3 factors determine stroke volume?
1) preload
2) afterload
3) contractility
What two factors determine preload?
1) intravascular volume
2) venous tone
* when veins constrict, blood is diverted to the heart
What is the major determinant of intravascular volume?
the amount of sodium in the body
What hormone is most important for controlling intravascular volume?
aldosterone–> controls the Na+
What is the best equation for MAP if you know CO and SVR?
MAP = (CO x SVR)/80 + CVP
*this equation can be manipulated to find other values
Preload is the ________ present in the wall of the left ventricle at the end of diastole (immediately prior to contraction).
tension–> “tightness”–> force
*preload is d\t volume, but is not volume–> it is the tension in the wall
Preload is determined by the _______ of blood in the LV chamber at the end-diastole.
VOLUME–> but it is the tension not volume
Afterload is the _______ in the wall of the heart at the time the ______ valve opens.
tension–> force at the time the aortic valve opens
* “After”load–> after systole starts
Afterload is determined by ___________.
SVR…… SVR= PRESSURE
- the > the SVR, the > the afterload
- afterload is d\t the SVR (pressure) on the other side of the valve but is actually the tension on the wall after systole begins
The _______ the SVR, the _______ the afterload.
> SVR=>afterload
When afterload increases, SV _______.
decreases
When preload increases, SV ________.
increases
The > the ventricular filling (volume), the ________ the preload (tension). What explains this?
greater–> this is d\t Frank Starlings Law of the Heart
Where _____ goes, H2O follows.
sodium
When you hear preload think _______, afterload think _______, contractility think ________.
preload=volume
afterload=pressure
contractility=chemicals (inotropes, CCB’s, etc)
SV= _______ - _______.
EDV-ESV
EF= _____________
EF= (EDV-ESV)/EDV x 100
Contractility doesn’t influence _______, it influences ______.
filling–> it influences emptying
Where does angiotensinogen come from?
the liver
Where does renin come from?
the kidney (JGA); its dumped into the blood and affects angiotensinogen–> Ang1
Where is angiotensin converted enzyme (ACE) primarily found and what does it do?
LUNGS–> converts angiotensin I to II
Anytime you see “-ogen” as in angiotensinogen, think ______.
substrate
How can you easily remember the layers and products of the adrenal cortex?
AG (aldosterone–> zona glomerulosa)
CF (cortisol–> zona fasiculata) (glucocorticoids such as cortisol)
TR (testosterone–> zona reticularis)
*remember–> salt, sugar, sex (aldosterone, cortisol, testosterone)
Given you have filled the heart (preload) and that the aortic valve opens (afterload), can you squeeze better? This is contractility. It is determined by the CHEMICAL environment of the cardiac cell. What are some examples of chemicals that alter contractile function?
ions (calcium and magnesium), oxygen, acids, drugs, hormones
*when contractility increases, the ventricle empties MORE completely and SV increases
What is the difference between concentric and eccentric hypertrophy in relation to the size of the left ventricular chamber?
concentric= no change in the size of the LV chamber eccentric= increased size of the LV chamber
What law has to do with ventricular hypertrophy in response to pressure or volume overload?
law of Laplace
What happens during concentric hypertrophy?
LV wall thickens and chamber size remains same–> results from chronically elevated afterload (coarctation of aorta, chronic aortic stenosis, chronic untreated arterial HTN)
*IHSS is different than concentric hypertrophy b\c size of LV chamber would decrease
What happens during eccentric hypertrophy?
LV wall dilates, thus permitting the chamber to enlarge–> results from chronic requirement to pump large volumes of blood (mitral insufficiency, chronic aortic insufficiency, morbid obesity d\t increased volume)
What does coarctation mean?
“narrowing”
Name the 3 main causes of concentric hypertrophy.
1) coarctation of the aorta
2) chronic untreated HTN
3) chronic aortic stenosis
* pressure challenge on the heart
Name the 3 main causes of eccentric hypertrophy.
1) chronic aortic regurgitation
2) chronic mitral regurgitation
3) morbid obesity (50ml/kg–> but they have a lot of kg!)
* volume overload issue
Easy way to remember Law of Laplace…..?
TP for the rectum
T=p x r
*explains ventricular hypertrophy in response to volume or pressure
What is the x axis on the ventricular pressure-volume loop?
VOLUME
What is the y axis on the ventricular pressure-volume loop?
PRESSURE
If the ventricular pressure-volume loop becomes narrower or wider, what is being changed?
VOLUME
If the ventricular pressure-volume loop becomes taller or shorter, what is being changed?
PRESSURE
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does A represent?
mitral valve opens
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. There is normally a slight increase in pressure right before point B. What does this represent?
atrial kick (~25ml)
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does B represent?
mitral valve closes (“S1” sound– end of diastole, systole begins); EDV–> tension in the chamber is “preload” (all the volume is in and now pressure begins to build)
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does C represent?
aortic valve opens–> afterload d\t SVR (~80 DBP–> highest pressure that was reached before ejecting); ejection begins after point C, so volume begins to fall
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does the peak from point C to D represent?
The SBP (~120mmHg)–> highest pressure that was reached while ejecting
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does point D represent?
aortic valve closes (“S2” sound–> systole ends and diastole begins; also this is the ESV–> this point will show you contractility changes… b\c contractility has to do with the amount of blood ejected…. so if more blood is left, then contractility decreased
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does A-B represent?
diastolic filling; volume increases rapidly and pressure only increases slightly
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does B-C represent?
isovolumetric contraction; no change in volume, pressure builds rapidly
From bottom left to right and counterclockwise on the ventricular pressure-volume loop, the points go from A->B->C->D. What does C-D represent?
Systolic ejection; increase and then decrease in pressure as volume decreases rapidly